1. Field of the Invention
This Nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 2003-20474 filed in JAPAN on Jan. 29, 2003, the entire contents of which are hereby incorporated by reference.
The present invention relates to a car navigation system for showing a driver a route to travel more plainly while driving.
2. Description of Related Art
A car navigation system provides a driver with guidance on the direction to proceed by speech or display when the vehicle approaches an intersection. However, two consecutive bifurcate intersections at a short distance, for example, can make the guidance confusing, thereby likely to mislead the driver.
To prevent such confusing guidance, the following relevant reference 1, for example, proposes a car navigation system that provides guidance easier to understand. It selects all the nodes, at which links with an attribute called an intra-intersection link join, from among the guidance nodes represented in map data, and integrates them to provide guidance considering these intersections as a single intersection.
Relevant reference 1: Japanese patent application laid-open No. 11-51674/1999, pp. 1-9.
As described above, there is such a conventional navigation system that collects all the nodes at which the links with the attribute called the intra-intersection links join, and provides guidance considering the plurality of intersections as a single intersection. In this case, as for the road data as to which the links do not have the attribute of the intra-intersection link, the foregoing technique is inapplicable. As a result, in such a case where two consecutive bifurcate intersections appear in a short distance, the driver can misunderstand the guidance, which presents a problem of misleading the traveling direction.